Livestock Parasites

Parasites cause a reduction in:

• fertility

• milking ability

• meat production

• wool production

• wool soundness

• immunity

River Fluke

• highly pathogenic in sheep, less of a problem in cattle

• major cause of production loss in cattle

• indirect life cycle - transmitted through mud snail

• life cycle dependent on temperature and rainfall

Epidemiology - Gut Worms

• all of these species have direct life cycles

• eggs shed on pasture in dung

• develop to L1—L2—L3 within dung pat

• development dependent on temperature, proceeds faster when it is warmer

• L3 is infective stage, migrates from dung to pasture

• L3 can survive over winter on pasture

• control based on preventing L3 development

Haemonchus Contortus (barber pole worm):

• fatal to sheep and goats

• causes lots of bleeding

• developed immunity to ivermectin

Clinical Signs of infection:

• anemia

• sub-mandibular enema “bottle jaw”

• loss of weight and condition

• weakness

• anorexia

life cycle

• eggs go from manure to pasture to food and then are eaten

Ostertagia Ostertagi

• Brown Stomach Worm, Cows and Calves

• 6-10mm

• severe diarrhea and weight loss

• recognized as most important nematode parasite of cattle raised in temperate climates

• can developmentally arrest in summer, emerge from arrest in autumn

• larvae destroy gastric glands upon emergence from arrest

• Large economic impact on cattle industry - treatment and prevention costs

What happens

• abomassal edema

• proliferation of bacteria in the abomassum

• depressed immunity

• fermentation in the small intestine

• fluid pulled into gut resulting in diarrhea

• dehydration

• primary digestion decreased

• anorexia